How do you populate 1 text box with multiple dropdown values

I can populate a text box with a value from a dropdown, however if I have 2 dropdown values going to the same text box (multi-line), the second dropdown value removes the first value.

(Similar code on Dropdown 1 and Dropdown 2)

Change Event - JavaScript

if(xfa.event.newText == 'No'){

form1.page1.subform2.description.rawValue="No location listed";

}

if(xfa.event.newText == "Partial location"){

form1.page1.subform2.description.rawValue="Partial location listed";

}

Do I have to Concat the fields in the 1 text field to get it to list multiple dropdown values, and if so how do I do that?

Thanks in advance for your help.